Title:
Strengths of Recycled Aggregate Concrete Made Using
Field-Demolished Concrete as Aggregate
Author(s):
Mostafa Tavakoli and Parviz Soroushian
Publication:
Materials Journal
Volume:
93
Issue:
2
Appears on pages(s):
178-181
Keywords:
aggregates; compressive strength; demolition; flexural
strength; recycling; splitting tensile strength.
DOI:
10.14359/9802
Date:
3/1/1996
Abstract:
Experimental work was performed to determine the compressive, splitting tensile, and flexural strengths of recycled coarse aggregate concrete and to compare them with those of concrete made using natural crushed stone. The properties of the aggregate were also compared. The fine aggregate for recycled and conventional concrete was 100 percent natural sand. Two sources of recycled aggregate (crushed concrete pavements from U.S. 23 and 1-75 projects in Michigan) and one source of natural aggregate (crushed limestone) were used. Two maximum sizes of aggregates, two levels of water-cement ratio, and two levels of dry mixing time of coarse aggregate were selected to perform the experiments based on a full factorial design. Test results indicate that the strength characteristics of recycled aggregate concrete are influenced by key factors, such as the strength of the ori-inal concrete, the ratio of coarse to fine aggregate in the original concrete, the ratio of top size of aggregate in the original concrete to that of the recy-cled aggregate, and the Los Angeles abrasion loss and water absorption of recycled aggregate. These factors also influence the effect of water-cement ratio, aggregate top size, and dry mixing on the strength characteristics of recycled aggregate concrete. It is also shown that the conventional rela-tionships between splitting tensile, flexural, and compressive strengths may have to be modified for recycled aggregate concrete. The final conclusion is that through proper measures high-quality concrete materials can be produced using recycled concrete aggregate. For this purpose, it is needed to determine the properties of the original concrete, based on which realistic qualities can be targeted for recycled aggregate concrete.